Colour and turbidity removal with reusable magnetite particles—V: Process development

A process design has been developed for a continuous process to clarify turbid and coloured waters with alkali treated magnetite. Critical parts of the process have been investigated in small bench scale equipment, and criteria determined for the proper selection of equipment. A continuous pilot plant which appears to be both technically and economically feasible has been specified from the process design, and will be the subject of further investigations.     

Colour and turbidity removal with reusable magnetite particles—VI: Pilot plant operation

A novel process which utilizes fine magnetite particles for the removal of colour and turbidity from water has been tested in a 60 1 min⁻¹ pilot plant on water from an unconfined aquifer in Perth, Western Australia. The performance of the pilot plant closely matched jar test results. The process design was optimized to achieve a high quality product water on a raw feed which was difficult to treat in the conventional alum coagulation and filtration plant. A comparison of the conventional and magnetite treatment systems is made, which shows that the magnetite process is viable as an alternative water treatment technique.     

Colour and turbidity removal with reusable magnetite particles—IV: Alkali activated magnetite—A new solid. Reusable coagulant-adsorbent

Alkali treated magnetite (Fe₃O₄) is shown to be an excellent solid coagulant-adsorbent which is regenerable and reusable. It is effective for the removal of colour and turbidity from water. Alkali treated magnetite can be used alone or in conjunction with another primary inorganic coagulant or organic flocculant. Because of the accelerated kinetics of coagulation and particularly of sedimentation, this new technique is 3–6 times faster than the conventional coagulation-flocculation-sedimentation process. It also appears that filtration of the product water may not be necessary. Regeneration of the spent magnetite is achieved by contacting the used magnetite with 0.1 M sodium hydroxide. The development of the process on the laboratory scale using a jar test technique is discussed.     

Colour and turbidity removal with reusable magnetic particles—I. Use of magnetic cation exchange resins to introduce aluminium ions

Clarification of hard, turbid surface water by Al³⁺ ions introduced on a sulphonic acid ion exchanger is described. If the resin beads are sufficiently fine, they act as nuclei for floc formation and accelerate the subsequent settling of the flocs. Incorporation of magnetic iron oxide in the resin beads enables them to be conveniently separated from the clarified water. Acidification of the resin-containing sludge then results in partial reloading of the resin with Al³⁺ ions. However, the regenerated resin proved ineffective as a coagulant, a result attributed chiefly to hydrolysis of Al³⁺ ions within the resin. The findings of this work are significant for the theory of coagulation and also suggested the possibility of enhancing clarification by adding fine particles with an absorbing surface.     

A comparison between occupants’ and inspectors’ reports on home dampness and their association with the health of children: The ALLHOME study

There is some discussion concerning the methodology to be used in order to obtain health-relevant information regarding moisture-related problems in homes (dampness). Occupants’ reports, inspectors’ observations and physical measurements are often used methods. In the current study, data on dwelling dampness and characteristics as reported by parents of 216 pre-school children (the cross-sectional questionnaire study ALLHOME-1) was compared with the information collected by non-professional dwelling inspectors in a nested case–control study (the ALLHOME-2 study). The study took place in the cities of Burgas and Sofia in Bulgaria. The inspectors reported less visible mould, but more damp stains and a mouldy odour than the parents. Exposure to dampness, as reported by parents, was significantly associated with airways, nose and/or skin symptoms (case status) among children, while no association was found between inspectors’ observations on dampness and children's health. Parental reports on housing characteristics such as type of house, residential situation, and type of flooring material matched with those identified by the inspectors and therefore can be used as a reliable source of information in studies on indoor environmental exposure and health. With regard to dampness, parental reports seem to be more health relevant than inspectors reports.     

A study on a porous residential building model in hot and humid regions: Part 1—the natural ventilation performance and the cooling load reduction effect of the building model

This study targets environmental load reduction in hot and humid regions. It reveals the effects that porous residential buildings have on the natural ventilation performance and, consequently, the cooling load reduction. Two residential building models, namely a model with a void ratio of 0% and a model with a void ratio of 50%, are evaluated using computational fluid dynamics (CFD) analysis and thermal and airflow network analysis. The analysis on components of the heat load indicates that improvements in the natural ventilation performance would significantly reduce the cooling load.